Semiconductor Memory Program Speed via Continuous Word Line Voltage
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Solution Overview
Problem
The existing semiconductor memory devices face inefficiencies in program speed due to the need for precharge and discharge operations during verify and program operations, which increase the time required and hinder faster programming.
Innovation Solution
The proposed method involves performing a verify operation on selected memory cells by applying a selected word line voltage, continuously increasing it to a program voltage level without discharging, and applying a program inhibit voltage to bit lines, while also increasing unselected word line voltages to a program pass voltage level, thereby eliminating the need for discharging between operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If precharge and discharge operations are performed during verify and program operations, then voltage levels can be changed to desired levels, but the time required for programming increases
Solution Approach 1:
The word line is pre-charged to a high voltage level before the verify operation. This preliminary charging action eliminates the need for re-charging during subsequent verify and program operations, as the word line already holds the necessary voltage. The discharge operation is also performed in advance, so the word line is ready for immediate use in the next operation cycle.
Solution Approach 2:
The patent implements continuous voltage application on the word line throughout the verify and program operations without interruption. By maintaining the high voltage level on the word line continuously and eliminating the discharge phase between operations, the useful action of voltage application becomes uninterrupted, thereby reducing the total time required for programming while ensuring reliable voltage control.
2Productivity
If word line voltage is increased continuously without discharging, then program speed increases, but voltage control precision may be compromised
Solution Approach 1:
The patent employs dynamic voltage control where the word line voltage is continuously adjusted and increased during the programming operation. The voltage starts at a lower level for the verify operation and then continuously rises to the required program voltage level. This dynamic approach allows the system to maintain precise voltage control at each stage while achieving high program speed through continuous voltage increase without discharge.
Solution Approach 2:
The patent changes the voltage parameter dynamically during the operations. Instead of using fixed voltage levels with discrete charging and discharging, the word line voltage is continuously varied from lower levels during verify to higher levels during program. This parameter change strategy enables both precise voltage control for reliable operation and fast programming speed by eliminating the discharge phase.
Data Source
AI summary
A program method of a semiconductor memory device includes performing a verify operation on selected memory cells by applying a selected word line voltage to a selected word line, continuously increasing the selected word line voltage without discharging the selected word line after the verify operation, and performing a program operation on the selected memory cells when the selected word line voltage reaches a program voltage level.